Study site and species
The study was conducted at the Qianyanzhou Experimental Station of Red Soil and Hilly Land, Chinese Academy of Sciences (26°44N, 115°03E, 102 m a.s.l.), Jiangxi Province, southeastern China. This area has a typical subtropical climate, with mean annual temperature and precipitation of 17.9 °C and 1475 mm, respectively (Wen et al. 2010). The parent soil, weathered from red sandstone and mudstone, is classified as Inceptisol, according to the USDA soil taxonomy. The forest was restored in 1985 by planting tree species such as slash pine (Pinus elliottii Englem) and Chinese fir (Cunninghamia lanceolata Hook) (Wang et al. 2012). In this study, we selected 15 tree species belonging to 13 genera and 9 families, with 8 AM species and 7 ECM species representing the local plant communities (Table S1).